Android，无法从互联网应用接收数据

Question

I am completely new to android. I am trying to build a basic app to get an idea on "android applications reading data from a server". To get an idea about http connection on android i created this app watching a video tutorial, i have two java classes.

HttpExample.java class,

package com.raveen.testingthree;

import android.app.Activity;
import android.os.Bundle;
import android.os.StrictMode;
import android.view.View;
import android.widget.TextView;

public class HttpExample extends Activity {

TextView httpStuff;

@Override
protected void onCreate(Bundle savedInstanceState) {
    // TODO Auto-generated method stub
    StrictMode.ThreadPolicy policy = new StrictMode.ThreadPolicy.Builder()
            .detectAll().penaltyLog().build();
    StrictMode.setThreadPolicy(policy);
    super.onCreate(savedInstanceState);
    httpStuff = (TextView) findViewById(R.id.tvHttp);
    GetMethodHttp test = new GetMethodHttp();
    String returned;
    try {
        returned = test.getInternetData();
        httpStuff.setText(returned);
    } catch (Exception e) {
        // TODO Auto-generated catch block
        e.printStackTrace();
    }

}



}

and getmethodhttp.java class,

package com.raveen.testingthree;

import java.io.BufferedReader;
import java.io.InputStreamReader;
import java.net.URI;

import org.apache.http.HttpResponse;
import org.apache.http.client.HttpClient;
import org.apache.http.client.methods.HttpGet;
import org.apache.http.impl.client.DefaultHttpClient;

public class GetMethodHttp {

public String getInternetData () throws Exception{
    BufferedReader in = null;
    String data = null;

    try{
        HttpClient client = new DefaultHttpClient();
        URI website = new URI("http://www.google.com");
        HttpGet request = new HttpGet();
        request.setURI(website);
        HttpResponse responce = client.execute(request);

        in = new BufferedReader(new InputStreamReader(responce.getEntity().getContent()));
        StringBuffer sb = new StringBuffer("");
        String line = "";
        String newLine = System.getProperty("line.separator");

        while((line = in.readLine()) != null){
            sb.append(line + newLine);

        }
        in.close();
        data = sb.toString();
        return data;

    } finally {
        if (in != null){
            try{
                in.close();
                return data;
            } catch (Exception e){
                e.printStackTrace();
            }
        }
    }
}

}

this is my AndroidManifest,

<uses-sdk
    android:minSdkVersion="15"
    android:targetSdkVersion="22" />

<uses-permission android:name="android.permission.INTERNET" />
<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE" />
<application
    android:allowBackup="true"
    android:icon="@drawable/ic_launcher"
    android:label="@string/app_name"
    android:theme="@style/AppTheme" >
    <activity
        android:name=".HttpExample"
        android:label="@string/app_name" >
        <intent-filter>
            <action android:name="android.intent.action.MAIN" />

            <category android:name="android.intent.category.LAUNCHER" />
        </intent-filter>
    </activity>

</application>


</manifest>

and my layout xml,

<?xml version="1.0" encoding="utf-8"?>
<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
android:layout_width="match_parent"
android:layout_height="match_parent"
android:orientation="vertical" >

<ScrollView
    android:layout_width="fill_parent"
    android:layout_height="fill_parent" >

    <TextView
        android:id="@+id/tvHttp"
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:text="Loading Data"
        android:textSize="20dp"
         />
</ScrollView>

</LinearLayout>

now when i run this on emulator or my android phone NOTHING IS DISPLAYED.. Just a blank white layout is visible.. what am i doing wrong here?

(i am using eclipse to program)

Answer 1

First of all you should not change the policy to force network calls on main thread instead use Async task .

If you want to read html contents then use jsoup which allows to parse html. If you want to read data from webservice then try VOLLEY Library.This will save your time,works more efficiently and traceable.